SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2cb49362205954bbf25d350fc824d959edcf9e1abefcf75d27c3f3cce4d4021b' 
  AND token = 'EOjAnAlSayNowU5Zw6hfjXkScyu4YqnrHipmvmRfEWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}